Gemmacrinus PROKOP et PETR, 1989

Prokop, Rudolf J. & Nohejlová, Martina, 2015, Unique Discovery Of The Crinoid Gemmacrinus Perplexus Prokop Et Petr, 1989 In The Lower Devonian, Koněprusy Limestone (Barrandian Area, The Czech Republic), Acta Musei Nationalis Pragae Series B 71 (1 - 2), pp. 15-16 : 16

Gemmacrinus PROKOP et PETR, 1989

Type species: Gemmacrinus perplexus PROKOP et PETR, 1989 . Lower Devonian , Bohemia , the Czech Republic.

Gemmacrinus perplexus PROKOP et PETR, 1989

Text-fig. 2

T y p e h o r i z o n: Lower Devonian, Pragian, Koněprusy

Limestone.

T y p e l o c a l i t y: Suchomasty, “Na Plešivci” quarry

(Central Bohemia, Czech Republic).

M a t e r i a l: Three specimens inside the gastropod conch (the specimen NM-L31684 is deposited in the collections of the Palaeontological Department of the National Museum, Prague), here described. Four isolated radial plates from washings from the weathered part of biosparitic Koněprusy limestones (from the Suchomasty , “ Na Plešivci ” quarry) and 17 isolated radials and basals from washings of the same weathered limestones from the Koněprusy , Čertovy Schody-West Quarry .

D e s c r i p t i o n: Almost entire calyx of the Gemmacrinus perplexus PROKOP et PETR, 1989 is high, slender, bowl shaped, with convex base (see Ubaghs 1978, p. T99). Basals poorly visible, mostly covered by limestone coquine. Radial plates elongated, interradial processes slim, forming ca. 1/3 height of radials. Radial notches generally narrow, minute, radial facets small, the fulcral ridges not visible.

R e m a r k s: The slender radial plates, elongated IRR processes and minute radial facets of gemmacrinid calyxes here described and are identical with the isolated radials of Gemmacrinus perplexus found rarely in the washings from biosparitic limestones of the “Chapel Horizon”, Zlíchovian ( Prokop and Petr 1989).

Figures

Text-fig. 2. Gemmacrinus perplexus PROKOP et PETR, 1989. A – Specimen NM-L31684; cavity of the conch of gastropod Epiptychia? PERNER, 1911 with preserved calyxes of crinoid Gemmacrius perplexus PROKOP et PETR, 1989. Scale bar represents 5 mm. B – The same specimen; best preserved calyx in detail. Lower Devonian, Pragian, Koněprusy Limestone, Suchomasty, “Na Plešivci” quarry. Scale bar represents 1 mm.